Recently, various improvements or modifications on coelectrophotography machines or printers utilizing electrophotography have been desired as these machines have become more popular. For example, it has been desired to reduce energy consumption in order for these machines to be practical for home use. It is also desirable to make the machines run at high speeds in order to promote the spread of the machines into so called gray areas between printers and copiers. It is also necessary to simplify the structure of the machine in order to reduce the cost of the machines. Moreover, it has become popular to use the machines having functions of printing on both sides of the printed sheet and delivering the printed sheet automatically. Of the above-described requirements, particularly desired is a toner for electrophotography (hereafter, referred to simply as "toner") having a lower fixing temperature, a good anti-offset quality and fixing strength so that spots are not generated in a printed sheet in printing both sides of the printed sheet.
Polyolefines having a low molecular weight have generally excellent cold resistance, heat resistance, chemical resistance, abrasion resistance, and the like; therefore, they have been used as workability improvers for rubbers and plastics, dispersing agents for printing inks, abrasion resistance improvers, blocking resistance improvers, lustering agents, removers, electrical insulating materials, preservatives, and the like.
In an electrophotography field, polyolefins has received much attention as a remover among these uses; therefore, polyolefins are widely used to prevent the offset phenomenon of toners used in printers or copiers.
Moreover, in general, a polyolefin is easily handled, because its viscosity is low when it is melted. On the other hand, its compatibility with other resins and with solvents is poor; therefore, it has been desired to improve its compatibility.
Concretely, when an olefin resin is used alone in a binder resin comprising a toner as a main component, it is difficult to obtain both an anti-offset property and good fixing property. Therefore, it is impossible to use only olefin resin as a binder resin of a toner. Accordingly, when olefin resins such as styrene-acrylic copolymer and polyester resin are used as a binder resin, a remover should be mixed in at a range of 1 to 10 weight % with regard to the amount of olefin resin. However, the remover cannot be uniformly dispersed into the binder resin.
In order to solve this problem, it is suggested to improve the compatibility of olefin resin with other resins by copolymerization of olefin monomer and polar monomer, oxidative deconstituent of polyolefin, introduction of polar group by chemical denaturation, and the like.
A certain degree of its compatibility and dispersibility can be improved by introducing a polar group into polyolefin. However, it is difficult to obtain such an effect for some kinds of polyolefin.
Problems to be solved
Therefore, it is an object of the present invention to provide new olefin resin having excellent compatibility with other resins, in addition to a low melting temperature, and a low viscosity by improving conventional olefin resins. Moreover, it is also an object of the present invention to provide a toner having no offset phenomenon, and excellent fixing strength to a transfer paper by using the improved olefin resin as a binder resin of a toner.